Self-cooling bag for liquids



April 18, 1950 w. L. HlcKs 2,504,124

SELF'COOLING BAG FOR LIQUIDS Filed July 15, 1944 Inf Enron Wilhelm L.H|ck.r

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E moR/y y Patented Apr. 18, 1.950

A I 2,504,124 sm-coonmc BAG non mourns William L. Hicks, United States Greenville, s. 0.

Application July 15, 1944, Serial No. 545,174

7 Claims. (Cl. 150-1) I (Granted under the act of March 3, 1883, as

amended :30, 1928; 370 0. G. 757) The invention described herein, if patented may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to evaporative cooling devices, and more particularly to evaporative cooling devices constructed of fabrics impregnated with a highly polymeric material having hydrophilic substituents in a molecular weight range sufliciently high to prevent solution in water, or at least make the rate of water solubility extremely slow, and yet, permit diffusion of water therethrough.

Evaporative cooling devices constructed of fabrics are well known in the art. These devices, however, are unsatisfactory in that they do not inhibit the free flow of water through the fabric, thereby dissipating the water supply as well as decreasing the evaporative cooling effect. Although devices of this type have been constructed of linen fabrics to form a fairly satisfactory device owing to the hydrophilic properties inherent in the natural resins contained in the linen fibers, a notable increase in cooling effect and more rapid wetting is accomplished by treating such fabrics with hydrophilic materials as disclosed hereinafter. It is of equal importance that the bag should inhibit the free flow of water therethrough in order to conserve the water supply as well as assure maximum cooling by evaporation of water from the outside surface.

In selecting a material for impregnating fabrics purchasable in the open market there should be kept in mind that the material should be polymeric, selected from the class of high polymers having hydrophilic substituents in a molecular weight range sufficiently high as to be relatively water insoluble. The material, likewise, must permit diffusion, but inhibit the free flow of water therethrough. In addition to these properties the material must be adhesive to the fabric.

In the preferred embodiment, the fabric is impregnated with the hydrophilic material prior to manufacture of the bag. By the expression impregnating" it is intended to include the usual coating processes as well as the impregnating processes well known in the art. It has been found that the best effect may be obtained by impregnating the fabric by a padder process followed by coating one side of the finished fabric. Many natural gums, synthetic gums, and synthetic resins have been found to be satisfactory as impregnating compositions when used in wasoluble properties.

solubility properties of the particular resins. Purified methyl cellulose admixed with polymethyl methacrylate in a water-alcohol disper sant was found to be an excellent impregnating and coating composition. Gum tragacanth in a water dispersant and locust bean gum in a water dispersant were likewise found to be very satisfactory. Many materials, such as gum arabic, possess the desired hydrophilic property, but wash out of the fabric too quickly. Compounds of this nature should be admixed with other materials possessing greater adhesive and water in- Among the various materials which have been found to be satisfactory alone or in combination with other materials are incompletely acylated cellulose with a suitable plasticizer such as triacetin in a suitable organic dispersant, incompletely methylated methyl cellulose preferably in an organic dispersant, incompletely etherified hydroxyethyl cellulose in an alkaline solution and fixed by acidification and washing, carboxy methyl cellulose in an alkaline solution and fixed by acidification and washing,- highly viscous polyvinyl alcohol insolubilized, after application, by a formaldehyde treatment, partially hydrolized highly viscous polyvinyl acetates, polymethyl or polyethyl acrylates or methacrylates, sodium alginate, and

ter or organic dispersants depending upon the the salts, preferably sodium salt, of extremely viscous polyacrylic acid thickened with metallic hydroxides such as an aluminum or calcium hydroxides.

Many types of fabrics and weaves of fabrics have been tested and found satisfactory. The fabric found to be the most satisfactory is a closely woven oxford weave cotton material. However all of the duck or canvas materials tested were found to be adequate.

As specific examples of products and processes for treating fabrics the following are mentioned:

:1. A 24 oz. cotton duck fabric, which was previously dyed and dried, was run through a mixture of 8 oz. of gum tragacanth per gallon of water, on a padder having 50 lb. weights attached. The fabric was then dried on a loop drier at a temperature below that which would scorch the gum.

2. In a process similar to that above, methyl cellulose admixed with polymethyl methacrylate was used to impregnate fabric, followed by coating one side of the .impregnated fabric.

3. In a process similar to that above, 2402. twill canvas fabric was impregnated with a euprammonium solution of .cellulose and .then coated with polymethyl methacrylate.

due to leakage. When such a loss did occur, it

was but a small amount, due to the period of time required for the'wetting out and swelling of the'hydrophilic material. As to the cooling effect the following results were recorded: The air temperature of the room wherein the tests were conducted. was maintained at 98 plusor minus 3 F., the relative humidity was maintained at 15.6 plus or minus 2.2% and a static head of 30 inches of water was maintained in the bag. The temperature of the water inside the bag gradually decreased until at the end of 9 hours it was at 80 F., and at the end of 11 hours it had dropped to 775 F. In another series of tests wherein the air temperature of the room was maintained at 99 plus or minus 4 F. and the relative humidity was maintained within the range of 9 to 15%, the temperature of the water within the bag had lowered to 73 F. at the end of hours. The loss of water due to evaporation was calculated and found to be slightly more than 0.2 cubic centimeter per hour per square centimeter of body bottom.

There are certain novel features of construction involved in the manufacture of the water bag as will now be describedin conjunction with the drawings wherein:

Figure 1 is a perspective view of the evaporative cooling device.

Figure 2 is a detailed sectional view along line 2-2 of Figure 1, showing the method of joining the body member to the supporting ring.

Figure 3 is a detailed sectional view along line 33 of Figure 1, showing the method of joining the body and bottom members.

surface excluding the top and In the drawings wherein like members are given the same reference number, a substantially cy- Iindrical impregnated and coated fabric .body member I having one end .thereof closed by a bottom member 2 and a removable closure 3 for the other or top end forms a collapsible desert water bag. The bottom member 2 is reinforced with a heavy fabric layer 4 as is the lower portion of the body member I. The body member I has the reinforcing strip 4 extending upwardly, approximately 6 inches, so as to provide a reinforcement for faucets 5, which are inserted watertight near the bottom of the body member I.

The method of joining the bottom and body members, as illustrated in Figure 3, is to stitch the bottom member and its reinforcing member 4 to the substantially cylindrical body member i and its reinforcing member 4, and then place a substantially water impervious channel-shape member 1 over the juncture and securely attach it thereto by any of the known means, preferably stitching.

The transversal seam for joiningthe ends of the body member I is preferably formed in a similar manner. Another suitable means of joining the ends of the side member to form a substantially cylindrical body, however, is to overlap the edges and secure them together by mul- When this latter means is used it is desirable to employ a backing strip of relatively water impervious material.

In order to suspend the bag, there is provided a substantially circular, rigid supporting ring 8 having upwardly extending U-shaped sections or loops 8. The body member I is folded back upon itself and placed around the supporting ring i and the folded portions are securely stitched together, thereby reinforcing the fabric against suspension strain. Where the upwardly extending sections 9 of the supporting ring 8 appear, aligned apertures are provided in the body member I to permit the upwardly extending U-shaped sections 8 to extend therethrough. To avoid tearing at these apertures, reinforcing strips III are securely sewed to the body member I at these points.

The top member 3 is so constructed as to provide a downwardly extending iiap II divided in alignment with the upwardly extending-U-shaped sections 9 of the ring member Ii. The divided sections of the flap II are secured together by any suitable means such as snap fasteners or by having a belt I5 attached to one section and a buckle II to an adjacent section. By this construction the cover may be removed for filling the bag and then replaced and securely fastened so as to prohibit foreign material entering the water contained therein.

Having thus described the invention, '"hat is claimed is:

l. A. cylindrical two-piece evaporative cooling water bag capable of retaining water substantially without seepage loss, comprising a round bottom wall, and a cylindrical side wall of porous textile material, a hydrophilic substantially water-insoluble fabric-adhesive water-swellable polymeric coating on said textile material, said bottom wall and said side wall having turned flanges and united together to form a substanplastic coating on said textile material, said bottom wall and said side wall having turned flanges and united together to form a substantially waterimpermeable juncture between said bottom wall and said side wall; whereby leakage of water through said bottom wall and juncture is effectively stopped and evaporation of water through said side wall takes place at a slow controlled tiple stitching, as illustrated at 8 of Figure l.

rate without free flow of water so as to cool the water in the bag below ambient temperature.

3. A water bag according to claim 1, wherein said coating comprises a mixture of polymethyl Y 7. A cylindrical two-piece evaporative cooling water bag capable of retaining water substantially without seepage loss, comprising a round bottom wall, a cylindrical side 'wall of porous textile material, a hydrophilic substantially water-insoluble fabric-adhesive water-swellable poh'neric coating on said textile material, and a circular reinforcement strip at the lower margin of said side wall, said bottom wall and said reinforcement strip having turned flanges and united together to form a substantially water-impermeable juncture between said bottom wall and said side wall; whereby leakage of water through said bottom wall and juncture is effectively stopped and evaporation of water through said side wall takes place at a slow controlled rate without free" flow of water so as to cool the water in the bag below ambient temperature.

WILLIAM L. HICKS.

REFERENCES CITED The following references are of record in the file of this patent:

6 UNITED STATES PATENTS Number Name Date 135,432 Kelly Feb. 4, 1873 518,549 Lehman et a1 Apr. 17, 1894 994,287 Thorning June 6, 1911 1,127,384 Adams Feb. 9, 1915 2,220,525 Kauppi et al Nov. 5, 1940 2,271,885 Hathorne et al Feb. 3, 1942 2,275,991 Powers et a1 Mar. 10, 1942 2,323,629 Spanel July 6, 1943 2,337,398 Marsh et al Dec. 21, 1943 2,343,089 Smith Feb. 29, 1944 2,352,707 Goldthwait July 4. 1944 2,467,792 Wenzellet al Apr. 19, 1949 OTHER REFERENCES 

